Personally I love Cabbage beach and it is what we do when we are in Nassau. We have taken several modes of transport.
There is a boat taxi that you can take and it will drop you off across the street from the Atlantis Marina. From there you can walk through part of Atlantis to the "free beach" access. It is nice to stop and get a few trinkets inside the Atlantis gift shop etc. There are also stores and ice cream stops etc in the Marina area. The tickets for the boat taxi are sold inside the welcome center. I will be honest though and say I prefer taking this back but not to Atlantis as they wait to fill the boat and that can take awhile.
The other mode is just regular taxi to the "free beach" pretty easy and direct to the drop off which is a small path in-between hotels adjacent to Atlantis. Getting back is easy as well as there are loads of taxis hanging out ready to take you back to the ship.
On the beach they rent chairs for usually $10 and umbrellas as well for about the same amount. There are vendors so be prepared however I will say they are no worse than any other public beach I have been to in the Caribbean. They are usually friendly enough and leave you alone once you have said no to several of them.
There are no restrooms by the beach but honestly never been a big deal as we only stay for a few hours and then if we need them we head over to the marina area and use them and grab a treat! The waves can be pretty strong depending on when you are going however the water is beautiful. It really is a pretty beach and we always have fun!